Dongdaemun

A hangover-soup (haejangguk) restaurant on the ground floor of 249-20 Jangchungdan-ro, 165m from Dongdaemun History & Culture Park Station Exit 14. It opens at 05:00 every day, so it works for an early breakfast on the Dongdaemun side. The house haejangguk is ₩12,000, or ₩17,000 for the large; pork belly is served only after 17:00. 2026 blogs say it got busy after a TV appearance, with queues at lunch and on weekends, and that quite a few customers are foreign.

An ox-bone soup (seolleongtang) restaurant at 299-1 Jong-ro, 48 m from Dongdaemun Station Exit 1, open 24 hours every day of the year, so it works before dawn or early in the morning. Seolleongtang is ₩12,000, the large ₩15,000, and blood-curd hangover soup ₩9,000. Its Kakao Map rating is on the low side at 2.4 (27 reviews). Kakao Map and Naver both list it as open 00:00–24:00 every day, and two 2026 blogs say the same.

An Isaac Toast (toast-sandwich chain) on the ground floor of 43 Jangchungdan-ro 13-gil, 395m from Dongdaemun History & Culture Park Station Exit 14. Blogs place it right in front of Hyundai City Outlet, next to the entrance to the National Medical Center. Open 08:00–19:30 daily with a break 15:00–16:00. Ham and cheese toast is ₩3,100 and Bacon Best ₩3,900 (Naver menu). An October 2026 blog says foreign visitors queue for the opening every morning. The shop is small, so plan on takeaway.

A mayak gimbap stall (mini rice rolls with a mustard dipping sauce) inside Gwangjang Market at 403-23 Dongho-ro, 102m from Jongno 5-ga Station Exit 7. It opens at 09:00 every day and closes at 21:00, which makes it one of the earlier options for a market breakfast; it closes early when it runs out. Mayak gimbap is ₩4,000 and a mung-bean pancake (bindaetteok) ₩6,000 (Naver menu). From Dongdaemun Station it is about 0.9km, a 10–15 minute walk.

A Paris Baguette (bakery chain) on the ground floor of 305 Jong-ro, 15m from Dongdaemun Station Exit 2, open 24 hours (Kakao Map and Naver both list this). From 23:00 to 07:00, though, it runs unstaffed. You can buy bread and drinks before dawn, but whether a foreign card works during the unstaffed hours is unconfirmed. Prices are not shown on Kakao Map or Naver.

A bakery cafe in the Design Market on basement level 2 of DDP (Dongdaemun Design Plaza), 191m from Dongdaemun History & Culture Park Station Exit 1. DDP opens at 10:00, but this shop opens at 07:30 or 08:00, so you can have bread and coffee before looking around. A butter croissant is ₩3,900, an anbutter (red bean and butter) ciabatta ₩5,200 and an Americano ₩4,500 (Naver menu). There are separate men's and women's toilets inside the shop.

A bean-sprout soup (kongnamul gukbap) restaurant at 302 Jong-ro, 47m from Dongdaemun Station Exit 5. Open 07:00–17:30 Monday to Saturday, closed Sunday. Prices are low: beef bean-sprout rice and dried-pollack bean-sprout gukbap are ₩7,000, bean-sprout bibimbap ₩5,000 (₩1,000 extra for a large), and a blog notes a "good-price business" sticker. You pay first.